CN103685122A - Frequency error detection device, frequency error detection method, and receiving device - Google Patents
Frequency error detection device, frequency error detection method, and receiving device Download PDFInfo
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- CN103685122A CN103685122A CN201310376221.4A CN201310376221A CN103685122A CN 103685122 A CN103685122 A CN 103685122A CN 201310376221 A CN201310376221 A CN 201310376221A CN 103685122 A CN103685122 A CN 103685122A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
- H04L27/266—Fine or fractional frequency offset determination and synchronisation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2668—Details of algorithms
- H04L27/2669—Details of algorithms characterised by the domain of operation
- H04L27/2672—Frequency domain
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2668—Details of algorithms
- H04L27/2673—Details of algorithms characterised by synchronisation parameters
- H04L27/2675—Pilot or known symbols
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2668—Details of algorithms
- H04L27/2681—Details of algorithms characterised by constraints
- H04L27/2684—Complexity
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0024—Carrier regulation at the receiver end
- H04L2027/0026—Correction of carrier offset
- H04L2027/003—Correction of carrier offset at baseband only
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0044—Control loops for carrier regulation
- H04L2027/0053—Closed loops
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0044—Control loops for carrier regulation
- H04L2027/0063—Elements of loops
- H04L2027/0065—Frequency error detectors
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0083—Signalling arrangements
- H04L2027/0085—Signalling arrangements with no special signals for synchronisation
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- H—ELECTRICITY
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0083—Signalling arrangements
- H04L2027/0089—In-band signals
- H04L2027/0093—Intermittant signals
- H04L2027/0095—Intermittant signals in a preamble or similar structure
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Abstract
The invention provides a frequency error detection device, a frequency error detection method, and a receiving device, being capable of detecting frequency error by relatively low computation. A first frequency error detecting portion (21) is provided with a known signal extraction portion (31), a complex operation portion (32), a reference signal supplying portion (33), a correlation operation portion (36), and a peak detection portion (37). The known signal extraction portion (31) extracts and receives known signals from symbol signals. The complex operation portion (32) executes first complex operation on a sequence receiving the know signals to eliminate phase rotation components. The reference signal supplying portion (33) provides a reference complex signal sequence which is generated by executing a same operation with first complex number operation on a sequence of the known signals. The correlation operation portion (36) calculates distribution of cross-correlation values between an output sequence of the complex operation portion and the reference complex signal sequence. The peak detection portion (37) detects a distribution with a maximum peak in the distributions so as to detect frequency error of carrier waves.
Description
Technical field
The present invention relates to using signal that a plurality of subcarriers transmit according to frequency division multiplexing mode to receive and detect the technology of the error that this reception signal comprises.
Background technology
Generally speaking, generate in the receiver of baseband receiving signals of base band the reception signal of carrier frequency band (reference carrier frequency) being carried out to quadrature demodulation, when there is error (below also referred to as " frequency error ") between the carrier frequency of using and the carrier frequency of reception signal in quadrature demodulation, may wrongly reproduce and send data.Therefore, this receiver has the function that detects frequency error and it is proofreaied and correct.
OFDM (OFDM:Orthogonal Frequency Division Multiplexing) mode is by mutual a plurality of subcarriers (subcarrier) in orthogonality relation being carried out to Digital Modulation, the multiplexing mode that generates transmitted signal, being widely adopted in digital broadcasting field and the communications field.Quadrature amplitude modulation) or DQPSK(Differential Encoded Quadrature Phase Shift Keying Quadrature Phase Shift Keying), QAM(Quadrature Amplitude Modulation the Digital Modulation adopting as OFDM mode, for example, can enumerate QPSK(Quadrature Phase Shift Keying::: differential coding Quadrature Phase Shift Keying).
The technology that receives input frequency error about OFDM is for example disclosed in No. 3556047 specification of Japanese Patent (patent documentation 1) and No. 4563622 specification of Japanese Patent (patent documentation 2).
The disclosed digital broacast receiver of patent documentation 1 have OFDM received to signal implement DFT(discrete Fourier transform (DFT)) DFT processing unit, the output that can process means according to DFT take the carrier spacing be unit detect frequency error the 1st frequency error detector and can be according to 2nd frequency error detector of the output detections carrier spacing of DFT processing unit with interior frequency error.Herein, the 1st frequency error detector and the 2nd frequency error detector are implemented IDFT(inverse discrete Fourier transformer inverse-discrete to the reception known signal extracting the output from DFT processing unit (phase reference symbol)) computing, and use its operation result to detect frequency error.
On the other hand, in patent documentation 2, disclose and can in the situation that Symbol Timing has produced timeliness error (symbol timing error), detect the OFDM demodulating equipment of this error.OFDM demodulating equipment calculates two-dimensional correlation function according to the complex symbol signal on the current frequency axis receiving and the contrast signal information corresponding with it, and according to this two-dimensional correlation function, detects frequency error and the symbol timing error of the complex symbol signal on frequency axis.Here, contrast signal information is that supposition has produced the situation of deviation of Symbol Timing and pre-stored information in memory in certain subcarriers.
No. 3556047 specification of [patent documentation 1] Japanese Patent (0037th～0042 section, Fig. 2 etc.)
No. 4563622 specification of [patent documentation 2] Japanese Patent (0025th～0030 section, Fig. 2 etc.)
The disclosed digital broacast receiver of patent documentation 1 is used IDFT(inverse discrete Fourier transformer inverse-discrete) detect frequency error, so the operand of this IDFT is larger, frequency error detection expends time in.Or, when the 1st frequency error detector and the 2nd frequency error detector are carried out to Hardware, there is the problem of the easy large-scale of its circuit structure.
On the other hand, in the disclosed OFDM demodulating equipment of patent documentation 2, must the contrast signal of each certain subcarriers is pre-stored in memory, if do not prepare a plurality of contrast signals in advance, the detection range of then symbol timing error is restricted.Therefore there is the problem of shortcoming practicality in the method for patent documentation 2.
Summary of the invention
In view of the foregoing, the object of the invention is to can be with frequency error detection device, the receiving system with this frequency error detection device and the frequency error detecting method of less operand detected carrier frequency error.
The frequency error detection device of the 1st mode of the present invention detected carrier frequency error in receiving system, described receiving system has: acceptance division, it receives and uses a plurality of subcarriers with the subcarrier frequency differing from one another to carry out the transmitted signal frequency division multiplexing, the reception signal of outgoing carrier frequency band from transmitter; Quadrature demodulation portion, it carries out quadrature demodulation and generates complex baseband signal described reception signal; And orthogonal transform portion, it implements orthogonal transform to described complex baseband signal, generates the complex symbol signal of frequency domain, and described frequency error detection device is characterised in that to have: known signal extraction unit, it extracts and receives known signal from described complex symbol signal; Complex operation portion, its sequence to described reception known signal is carried out the 1st complex operation, eliminates thus the phase rotating component of giving described reception known signal when described orthogonal transform; Contrast signal supply unit, it provides with reference to complex signal sequence, and this is by the identical known signal sequence of the known signal sequence to using in described transmitter, to carry out 2nd complex operation identical with described the 1st complex operation to generate with reference to complex signal sequence; Correlation operation portion, it calculates from sequence and described a plurality of distributions with reference to the cross correlation value between complex signal sequence of the complex signal of described complex operation portion output; And peak value test section, it detects the distribution with peak-peak from described a plurality of distributions, described a plurality of distribution is calculated with respect to the described relative position with reference to complex signal sequence on frequency axis by the described correlation operation portion repeatedly sequence of mobile described complex signal, described peak value test section, according to the departure of the described relative position corresponding with the distribution with described peak-peak, detects described carrier frequency error.
The receiving system of the 2nd mode of the present invention is characterised in that to have: acceptance division, its transmitted signal from transmitter receives the frequency division multiplexing that has used a plurality of subcarriers with the subcarrier frequency differing from one another, the reception signal of outgoing carrier frequency band; Local oscillator, its generation has the oscillator signal of local oscillation frequency; Quadrature demodulation portion, it uses described oscillator signal to carry out quadrature demodulation and generate complex baseband signal described reception signal; Orthogonal transform portion, it implements orthogonal transform to described complex baseband signal, generates the complex symbol signal of frequency domain; Known signal extraction unit, it extracts and receives known signal from described complex symbol signal; Complex operation portion, its sequence to described reception known signal is carried out the 1st complex operation, eliminates thus the phase rotating component of giving described reception known signal when described orthogonal transform; Contrast signal supply unit, it provides with reference to complex signal sequence, and this is by the identical known signal sequence of the known signal sequence to using in described transmitter, to carry out 2nd complex operation identical with described the 1st complex operation to generate with reference to complex signal sequence; Correlation operation portion, it calculates from sequence and described a plurality of distributions with reference to the cross correlation value between complex signal sequence of the complex signal of described complex operation portion output; And peak value test section, it detects the distribution with peak-peak from described a plurality of distributions, described a plurality of distribution is calculated with respect to the described relative position with reference to complex signal sequence on frequency axis by the described correlation operation portion repeatedly sequence of mobile described complex signal, described peak value test section detects described carrier frequency error according to the departure of the described relative position corresponding with the distribution with described peak-peak, and described local oscillator is so that the mode that described carrier frequency error reduces is controlled described local oscillation frequency.
The frequency error detecting method of the 3rd mode of the present invention is the frequency error detecting method of detected carrier frequency error in receiving system, the transmitted signal of described receiving system from transmitter receives the frequency division multiplexing used a plurality of subcarriers with the subcarrier frequency differing from one another the reception signal of outgoing carrier frequency band, described reception signal is carried out quadrature demodulation and generates complex baseband signal, described frequency error detecting method is characterised in that, there are following steps: from the complex symbol signal by described complex baseband signal enforcement orthogonal transform is generated, extract and receive known signal, the sequence of described reception known signal is carried out to the 1st complex operation, eliminate thus the phase rotating component of giving described reception known signal when described orthogonal transform, provide with reference to complex signal sequence, this is by the identical known signal sequence of the known signal sequence to using in described transmitter, to carry out 2nd complex operation identical with described the 1st complex operation to generate with reference to complex signal sequence, repeatedly mobile described with reference to complex signal sequence with respect to the complex signal sequence of the execution result as described the 1st complex operation the relative position on frequency axis, calculate described complex signal sequence and described a plurality of distributions with reference to the cross correlation value between complex signal sequence, from described a plurality of distributions, detect peak-peak, and according to the departure of the described relative position corresponding with described peak-peak, detect described carrier frequency error.
According to the present invention, inverse fourier transform is used in the impact of the phase rotating need to the time error when due to orthogonal transform not producing.Therefore, can significantly cut down operand.Therefore,, in the situation that realizing frequency error detection device with hardware, can realize small-scale and the low power consumption of its circuit structure.
Accompanying drawing explanation
Fig. 1 is the functional block diagram of schematic configuration that the receiving system of embodiment of the present invention 1 is shown.
(A) of Fig. 2～(C) is the figure of the structure of summary transmission frame that DAB standard is shown.
Fig. 3 is the functional block diagram of structure example that the 2nd frequency error detection portion of execution mode 1 is shown.
Fig. 4 is the functional block diagram of schematic configuration that the 1st frequency error detection portion of execution mode 1 is shown.
Fig. 5 is the functional block diagram of schematic configuration that the 1st complex operation portion of execution mode 1 is shown.
(A) of Fig. 6～(C) is the figure that summary illustrates the signal value corresponding with subcarrier frequency.
Fig. 7 is the functional block diagram of schematic configuration that the 2nd complex operation portion of execution mode 1 is shown.
Fig. 8 is the functional block diagram of schematic configuration that the correlation operation portion of execution mode 1 is shown.
(A) of Fig. 9 is the figure of the example that distributes of the cross correlation value when carrier frequency error being shown being zero, is (B) figure of an example of the cross correlation value distribution when carrier frequency error of existences+5 subcarrier is shown.
Figure 10 illustrates synchronizing symbol that the subcarrier using with every of embodiment of the present invention 2 is corresponding as the figure that processes the state of object.
Figure 11 is the functional block diagram of schematic configuration that the 1st frequency error detection portion of embodiment of the present invention 3 is shown.
Figure 12 is the functional block diagram of schematic configuration that the 1st frequency error detection portion of embodiment of the present invention 4 is shown.
Figure 13 is the figure that summary illustrates the synchronizing symbol in synchronizing symbol in the scope that distortion is large and the little scope of distortion.
Figure 14 is the functional block diagram of schematic configuration that the 1st frequency error detection portion of embodiment of the present invention 5 is shown.
Figure 15 illustrates with computer program to realize the 1st frequency error detection portion 21 of execution mode 1～5, the functional block diagram of the arithmetic unit of the structure during function of 21B～21D.
Figure 16 is the flow chart of an example that the treatment step of embodiment of the present invention 6 is shown.
Figure 17 is the flow chart of a part that the treatment step of execution mode 6 is shown.
Figure 18 is the flow chart of an example that the treatment step of embodiment of the present invention 7 is shown.
Label declaration
1: receiving system; 11: tuning portion; 12:A/D transducer (ADC); 13: local oscillator; 14: quadrature demodulation portion; 15: discrete fast Fourier transform portion (DFT); 16: differential demodulation section; 17: channel decoder; 18: Veterbi decoding portion; 19: Read-Solomon lsb decoder (RS lsb decoder); 20: source decoder; 21,21B～21D: the 1st frequency error detection portion; 22: the 2 frequency error detection portions; 31: synchronizing symbol extraction unit; 32,32C, 32D: the 1st complex operation portion; 33,33B, 33C, 33D: contrast signal supply unit; 34: known signal generating unit; 34B: signal storage portion; 35,35C, 35D: the 2nd complex operation portion; 36,36C, 36D: correlation operation portion; 37: peak value test section; 38,38D: scope selection section; 39: positional information storage part; 40: operand specifying part; 41: delay portion; 42: correlation operation portion; 43: equalization portion; 44: peak value test section; 45: operational part; 46: the 1 signal delay portions; 47: the 1 complex multiplication portions; 48: the 2 signal delay portions; 49: the 2 complex multiplication portions; 51: processor; 61: the 1 signal delay portions; 62: the 1 complex multiplication portions; 63: the 2 signal delay portions; 64: the 2 complex multiplication portions; 70: buffer; 71: complex conjugate portion; 72: complex multiplication portion; 73: real part accumulation portion; 74: imaginary part accumulation portion; 75: power calculation portion.
Embodiment
Below, with reference to accompanying drawing, various execution mode of the present invention is described.
Fig. 1 is the functional block diagram of Sketch that the receiving system of embodiment of the present invention 1 is shown.As shown in Figure 1, the receiving system 1 of present embodiment has reception antenna element Rx, tuning portion 11, A/D converter (ADC) 12, local oscillator 13 and quadrature demodulation portion 14.
Tuning portion 11 receives wireless signal via reception antenna element Rx.11 pairs of these wireless signals of tuning portion are implemented the analog receiving signal that the analog such as tuning processing generate carrier frequency band, and this analog receiving signal is outputed to A/D converter 12.A/D converter 12 is converted to digital received signal by the analog receiving signal of carrier frequency band, and outputs to quadrature demodulation portion 14.Digital received signal is by a plurality of subcarriers in orthogonality relation are each other carried out to Digital Modulation, the multiplexing multi-carrier signal generating.In the present embodiment, as multi-carrier signal, use especially OFDM (OFDM:Orthogonal Frequency Division Multiplexing) signal.
The 14 use oscillator signal Os of quadrature demodulation portion implement to the digital received signal of carrier frequency band the baseband receiving signals r(t that quadrature demodulation generates base band).Here, t r(t) represents the time.Baseband receiving signals r(t) be the complex signal being formed by in-phase component (In-phase component) and quadrature component (Quadrature component).In addition, by the complex representation representing by this complex signal, be that I+jQ(j is imaginary unit) time, in-phase component means the signal of this real I, quadrature component means the signal of the imaginary part Q that this is plural.
Transformat as receiving signal, for example, can adopt a kind of DAB(Digital Audio Broadcasting as ground digital audio broadcasting standard: the digital audio broadcasting) transformat of standard.(A) of Fig. 2～(C) is the figure of the structure of summary transmission frame that DAB standard is shown.As shown in Fig. 2 (A), each transmission frame is by synchronizing channel (Synchronization Channel) portion, FIC(Fast Information Channel: fast information channel in dab receiver) portion and MSC(Main
servicechannel: MSC) portion forms.The cycle of transmission frame is about 96 milliseconds.As shown in Fig. 2 (B), synchronizing channel portion comprises null symbol (Null) and phase reference symbol (PRS:Phase Reference Symbols).
Phase reference symbol (PRS) is used the sequence, for example pseudo-random binary symbol sebolic addressing (PRBS:Pseudorandom Binary Bit Sequence) that comprise known symbol signal to generate by transmitter (not shown).In addition, FIC portion is by 3 FIB(Fast Information Blocks: FIB) form.This transmission frame, except null symbol, consists of a plurality of OFDM symbols.
As shown in Fig. 2 (C), 1 OFDM symbol comprises: the significant character that comprises a plurality of data symbols of frequency division multiplexing; And the GI portion (protection interval parts) being formed by the identical redundant signals of signal of the end part with this significant character.Phase reference symbol (PRS) at least consists of 1 OFDM symbol.In addition, in the present embodiment, before GI portion is configured to next-door neighbour's significant character, but be not limited to this.For example,, after GI portion also can be configured to next-door neighbour's significant character.
In addition, k the subcarrier frequency f using in ofdm signal
kfor example by following formula, provide.
f
k＝fc+k×f
0
Wherein, f
0=1/Tu sets up.During Tu is the significant character of OFDM symbol, fc is reference carrier frequency.In addition, k is sub-carrier number, is that 0～N-1(N is positive integer) scope in arbitrary integer.Therefore, subcarrier frequency is spaced apart f
0and constant.
As shown in Figure 1, receiving system 1 has discrete fast Fourier transform portion (DFT) 15, differential demodulation section 16 and channel decoder 17.DFT15 carries out multi-point sampling to the baseband receiving signals of 1 significant character, and the baseband receiving signals of this sampling is implemented discrete fast Fourier transform and exported the complex symbol signal of frequency domain.In addition, can generate complex symbol signal with the orthogonal transform of other kinds beyond discrete fast Fourier transform.
As shown in Figure 1, the receiving system 1 of present embodiment has the 1st frequency error detection portion 21 of detected carrier frequency error and the 2nd frequency error detection portion (narrow frequency error-detecting portion) 22.The 2nd frequency error detection portion 22 has detects subcarrier frequency interval with the function of interior carrier frequency error, and the 1st frequency error detection portion 21 has the function of the carrier frequency error of the integral multiple that detects subcarrier frequency interval.
Fig. 3 is the functional block diagram that the structure example of the 2nd frequency error detection portion 22 is shown.As shown in Figure 3, the 2nd frequency error detection portion 22 has delay portion 41, correlation operation portion 42, equalization portion 43 and operational part 45.
At local oscillation frequency f
swith carrier frequency f
cbetween current existence in the situation of subcarrier frequency interval with interior carrier frequency error Δ f, baseband receiving signals r(t) comprise the phase error component shown in following formula (1) (=2 π Δ ft).
r(t)=s(t)exp(-j2π·Δf·t)…(1)
Wherein, s(t) be the baseband receiving signals component while there is not carrier frequency error Δ f.
As shown in Fig. 2 (C), the redundant signals in GI portion is identical with the signal of the end part of significant character, so following formula (2) is set up.
s(t)=s(t-Tu)…(2)
The coherent signal Corr(t being provided by following formula (3) can calculate in correlation operation portion 42).
Corr(t)=r(t)×r
*(t-Tu)=|s(t)|
2exp(j2π·Δf·Tu)…(3)
Therefore carrier frequency error Δ f, this coherent signal Corr(t) can obtain by following formula (4).
Wherein, tan
-1(x) represent the arctan function relevant to variable x, Re(Corr(t)) be coherent signal Corr(t) real part be in-phase component, Im(Corr(t)) be coherent signal Corr(t) imaginary part be quadrature component.
Receiving signal has and is subject to the impact of noise and multipath fading and the situation of distortion.In order to get rid of this impact, the 2nd frequency error detection portion 22 makes the equalization portion 43 of the output equalization of correlation operation portion 42 in having during GI portion.Operational part 45 can be used above formula (4) to calculate carrier frequency error Δ f according to the output of this equalization portion 43.In addition, operational part 45 offers local oscillator 13 by the frequency error signal Ds2 that represents carrier frequency error Δ f.In addition, the structure of the 2nd frequency error detection portion 22 is not limited to the structure shown in Fig. 3.
The structure of the 1st frequency error detection portion 21 then, is described.
Fig. 4 is the functional block diagram that the Sketch of the 1st frequency error detection portion 21 is shown.As shown in Figure 4, the 1st frequency error detection portion 21 has synchronizing symbol extraction unit 31, the 1st complex operation portion 32, contrast signal supply unit 33, correlation operation portion 36 and peak value test section 37.
Synchronizing symbol extraction unit 31 has from the complex symbol signal of the output as DFT15, extracts the synchronizing symbol corresponding with phase reference symbol (Fig. 2 (B)) as the function that receives known signal.Use F(f
k) represent and subcarrier frequency f
kcorresponding synchronizing symbol.Now, comprise synchronizing symbol component F (f
k) baseband receiving signals r(t) for example can enough following formulas (5) performance.
DFT15 can be by this baseband receiving signals r(t) implement the discrete Fourier transform (DFT) that N is ordered, such N synchronizing symbol F(f that export as follows
k) (k=0～N-1).
But, deviation (hereinafter referred to as the time error) t on the processing of DFT15 can generation time regularly and between phase reference symbol sometimes
0.This time error t
0for example may in the situation that DFT15 to baseband receiving signals r(t) timing of sampling departed from correct timing or to baseband receiving signals r(t) starting position of sampling occurred to depart from and produced.In DFT15, produced time error t
0situation under, be shown below, DFT15 exports synchronizing symbol F(f
k) added phase rotating component exp(-j2 π f
kt
0) after synchronizing symbol G(f
k).
Therefore, as shown in Fig. 6 (A), DFT15 output and each subcarrier frequency f
kcorresponding synchronizing symbol G(f
k).With the order of sub-carrier number to the 1st 32 serial input synchronizing symbol G(f of complex operation portion
0), G(f
1), G(f
2), G(f
3) ...The synchronizing symbol G(f that the 1st 32 pairs, complex operation portion inputs
k) carry out the 1st complex operation, eliminate phase rotating component exp(-j2 π f
kt
0).Fig. 5 is the functional block diagram of schematic configuration that the 1st complex operation portion 32 of present embodiment is shown.As shown in Figure 5, the 1st complex operation portion 32 has the 1st the 46, the 1st the 47, the 2nd signal delay portion 48 of complex multiplication portion and the 2nd complex multiplication portion 49 of signal delay portion.
The 1st signal delay portion 46 makes the synchronizing symbol of serial input to the 1 complex operation portion 32 postpone the amount of 1 subcarrier.To the 1st complex operation portion 32, input synchronizing symbol G(f
k) time, 46 outputs of the 1st signal delay portion are than synchronizing symbol G(f
k) the Lag synchronization symbol G(f that postpones the amount of 1 subcarrier
k-1).The 1st complex operation portion 32 is by Lag synchronization symbol G(f
k-1) and input synchronizing symbol G(f
k) complex conjugate G
*(f
k) complex multiplication export multiplying signal S(f
k).This multiplying signal S(f
k) by following formula (6), provided.
S(f
k)=G(f
k-1)G
*(f
k)=F(f
k-1)F
*(f
k)exp[-j2π(f
k-1-f
k)t
0)]…(6)
Therefore, as shown in Fig. 6 (B), 47 outputs and each subcarrier frequency f of the 1st complex multiplication portion
kcorresponding multiplying signal S(f
k).And the 2nd signal delay portion 48 makes from the multiplying signal S(f of the 1st complex multiplication portion 47 inputs
k) postpone amount the output of 1 subcarrier.To the 2nd signal delay portion 48, input multiplying signal S(f
k) time, 48 outputs of the 2nd signal delay portion are than multiplying signal S(f
k) the delay multiplying signal S(f that postpones the amount of 1 subcarrier
k-1).The 2nd complex multiplication portion 49 will postpone multiplying signal S(f
k-1) and input multiplying signal S(f
k) complex conjugate S
*(f
k) complex multiplication export multiplying signal D(f
k).This multiplying signal D(f
k) by following formula (7A), provided.
D(f
k)=S(f
k-1)S
*(f
k)…(7A)
Above formula (7A) is arranged to multiplying signal D(f
k) can be provided by following formula (7B).
D(f
k)=F(f
k-2)F
*(f
k-1)F(f
k)F
*(f
k-1)exp[-j2π((f
k-2-f
k-1)-(f
k-1-f
k))t
0]
…(7B)
Subcarrier frequency interval is constant.Therefore, above formula (7B) is arranged, shown in (7C), the multiplying signal D(f that can be eliminated after phase rotating component
k).
D(f
k)=F(f
k-2)F
*(f
k-1)F(f
k)F
*(f
k-1)…(7C)
Thus, as shown in Fig. 6 (C), 49 outputs and each subcarrier frequency f of the 2nd complex multiplication portion
kcorresponding multiplying signal D(f
k).
On the other hand, as shown in Figure 4, the sequence of the known synchronizing symbol that 33 pairs of contrast signal supply units are used in transmitter is carried out 2nd complex operation identical with above-mentioned the 1st complex operation, and export as its result, obtain with reference to complex signal R(f
k).Particularly, contrast signal supply unit 33 consists of the 2nd complex operation portion 35 that provides the known signal generating unit 34 of known synchronizing symbol to carry out the 2nd complex operation identical with above-mentioned the 1st complex operation with the output to this known signal generating unit 34.Fig. 7 is the functional block diagram that the schematic configuration of the 2nd complex operation portion 35 is shown.As shown in Figure 7, the 2nd complex operation portion 35 possess have the delay feature identical with the 1st signal delay portion 46 the 1st signal delay portion 61, have the complex multiplication function identical with the 1st complex multiplication portion 47 the 1st complex multiplication portion 62, there is the 2nd signal delay portion 63 of the delay feature identical with the 2nd signal delay portion 48 and there is the 2nd complex multiplication portion 64 of the complex multiplication function identical with the 2nd complex multiplication portion 49.
Fig. 8 is the functional block diagram that the schematic configuration of correlation operation portion 36 is shown.As shown in Figure 8, correlation operation portion 36 has and accumulates inputted multiplying signal D(f temporarily
k) and with reference to complex signal R(f
k) buffer 70.This buffer 70 is being exported with reference to complex signal R(f
k) sequence time, output make subcarrier position (sub-carrier number) relatively with reference to complex signal R(f
k) sequence to depart from i(i be integer) after multiplying signal D(f
k-i) sequence.Complex conjugate portion 71 output from buffer 70 inputs with reference to complex signal R(f
k) complex conjugate R
*(f
k).
Real part and the imaginary part of all subcarriers accumulated respectively by real part accumulation portion 73 and imaginary part accumulation portion 74.And power calculation portion 75 reads real part, reads the sequence of imaginary part calculated power value as the distribution of cross correlation value from imaginary part accumulation portion 74 from real part accumulation portion 73.When the value that is RC, imaginary part in the value of establishing real part is IC, performance number Pw is provided by following formula (8).
Pw=RC
2+IC
2…（8）
In addition, can substitute performance number Pw and as shown in the formula such calculated amplitude value Am shown in (9).
Am=（RC
2+IC
2）
1/2…（9）
The 1st mobile multiplying signal D(f of complex operation portion more than 32 time
k) sequence with respect to reference to complex signal R(f
k) the relative position (subcarrier position) of sequence on frequency axis generate a plurality of distributions, and offer the peak value test section 37 of Fig. 4.Peak value test section 37 can detect the distribution that performance number in a plurality of distributions that calculated by correlation operation portion 36 has peak-peak, and according to the departure detected carrier frequency error with this corresponding relative position that distributes.
(A) of Fig. 9 is the figure of the example that distributes of the cross correlation value when carrier frequency error being shown being zero, and (B) of Fig. 9 is the figure of the example that distributes of the cross correlation value while there is the carrier frequency error of amount of+5 subcarriers.In the situation that Fig. 9 (A) forms peak-peak when relative position is zero.In addition, in the situation that Fig. 9 (B), the known peak-peak that forms during for the position corresponding with+5 subcarriers at relative position.
Thus, the carrier frequency error of the integral multiple at subcarrier frequency interval detects in the 1st frequency error detection portion 21, and the frequency error signal Ds1 that represents this carrier frequency error is offered to local oscillator 13.
As described above, in the present embodiment, even if the 1st complex operation portion 32 in the 1st frequency error detection portion 21 has produced time error t in DFT15
0situation under, also generate and eliminated due to this time error
t 0 the multiplying signal D(f of the phase rotating component causing
k).In addition, correlation operation portion 36 is used this multiplying signal D(f
k) carry out correlation operation, peak value test section 37 can be used its operation result detected carrier frequency error.Thus, the carrier frequency error of the integral multiple at subcarrier frequency interval can detect in the situation that not carrying out inverse fourier transform in the 1st frequency error detection portion 21 of present embodiment.
The disclosed prior art of patent documentation 1 is in order to get rid of the impact of time error, the complex conjugate that receives signal and known signal is being carried out after complex multiplication, this multiplication result is being carried out to the impact that inverse fourier transform is got rid of the phase rotating component that time error causes.On the other hand, in the present embodiment, can in the situation that not carrying out inverse fourier transform, get rid of the impact of the phase rotating component that time error causes.
Therefore, in the present embodiment, can significantly cut down operand.Therefore,, realize the 1st frequency error detection portion 21 with hardware in the situation that, can easily realize small-scale and the low power consumption of its circuit structure.
In the OFDM receiving system in the past of recording at patent documentation 1, successively in mobile 1 subcarrier, carrying out correlation operation and inverse fourier transform.Here, the large multiplex BPSK(Binary Phase Shift Keying of known signal generally speaking: binary phase shift keying) or DQPSK modulate, in this situation, in correlation operation, do not need complex multiplication.In the situation that establish the subcarrier number of object symbol, be that N, mobile scope (detection range) are D, the operand of the complex multiplication that inverse fourier transform is required is as follows approx:
（N×log
2（N））×D/2。
On the other hand, the operand of the complex multiplication in present embodiment be the complex multiplication carried out by the 1st complex operation portion 32 and the 2nd complex operation portion 35 respectively operand, with the summation of the operand of the complex multiplication of being carried out by correlation operation portion 36, its number of times is as follows:
N×4。
Therefore, when being made as N=1024, D=200, the operand in the situation of the method for patent documentation 1 is about 1024000, and the operand in the situation of present embodiment is 4096.Therefore, the operand of present embodiment is compared with the operand of the method for patent documentation 1, is that it is about 1/250, can access larger reduction effect.
In addition, above-mentioned synchronizing symbol is with the signal after BPSK or DQPSK modulation mostly.In these cases, the complex multiplication of being carried out by the 1st the 32, the 2nd complex operation portion 35 of complex operation portion and correlation operation portion 36 is added equivalence with plural number in fact.Therefore, if optimize the structure of the 1st the 32, the 2nd complex operation portion 35 of complex operation portion and correlation operation portion 36 in conjunction with this situation, operation times becomes N * 2, therefore can expect further operand reduction effect.
Then, embodiments of the present invention 2 are described.Execution mode 2 is variation of above-mentioned execution mode 1.In execution mode 1, using synchronizing symbol corresponding to the subcarrier of the N with all as processing object, but can only using the synchronizing symbol of the subcarrier scope that predetermines as processing object.In this case, can realize further operand and cut down effect.For example,, in the situation that using synchronizing symbol corresponding to half subcarrier with N subcarrier as processing object, operand further can be cut to half.
Figure 10 illustrates synchronizing symbol G(f corresponding to the subcarrier with every
0), G(f
2), G(f
4), G(f
6) ... as the figure that processes the state of object.In this situation, the 1st signal delay portion 46 of Fig. 5 makes the synchronizing symbol of serial input to the 1 complex operation portion 32 postpone the amount of 2 subcarriers.To the 1st complex operation portion 32, input synchronizing symbol G(f
k) time, 46 outputs of the 1st signal delay portion are than synchronizing symbol G(f
k) the Lag synchronization symbol G(f that postpones the amount of 2 subcarriers
k-2).The 1st complex operation portion 32 is by Lag synchronization symbol G(f
k-2) and input synchronizing symbol G(f
k) complex conjugate G
*(f
k) complex multiplication export multiplying signal S(f
k).This multiplying signal S(f
k) by following formula (10), provided.
S(f
k)=G(f
k-2)G
*(f
k)=F(f
k-2)F
*(f
k)exp[-j2π(f
k-2-f
k)t
0)]…(10)
And the 2nd signal delay portion 48 makes from the multiplying signal S(f of the 1st complex multiplication portion 47 inputs
k) postpone amount the output of 2 subcarriers.To the 2nd signal delay portion 48, input multiplying signal S(f
k) time, 48 outputs of the 2nd signal delay portion are than multiplying signal S(f
k) the delay multiplying signal S(f that postpones the amount of 2 subcarriers
k-2).The 2nd complex multiplication portion 49 will postpone multiplying signal S(f
k-2) and input multiplying signal S(f
k) complex conjugate S
*(f
k) complex multiplication export multiplying signal D(f
k).This multiplying signal D(f
k) by following formula (11A), provided.
D(f
k)=S(f
k-2)S
*(f
k)…(11A)
Above formula (11A) is arranged to multiplying signal D(f
k) can be provided by following formula (11B).
D(f
k)=F(f
k-4)F
*(f
k-2)F(f
k)F
*(f
k-2)exp[-j2π((f
k-4-f
k-2)-(f
k-2-f
k))t
0]
…(11B)
Subcarrier frequency interval is constant.Therefore, above formula (11B) is arranged, shown in (11C), the multiplying signal D(f that can be eliminated after phase rotating component
k).
D(f
k)=F(f
k-4)F
*(f
k-2)F(f
k)F
*(f
k-2)…(11C)
Therefore, same with the situation of above-mentioned execution mode 1, correlation operation portion 36 can be used the multiplying signal D(f eliminating after phase rotating component
k) and corresponding to it complex signal R(f
k) execution correlation operation.Peak value test section 37 can be according to its operation result detected carrier frequency error.
Therefore, in the present embodiment,, using synchronizing symbol corresponding to the subcarrier of the N with all as processing object, therefore can not cut down operand.In addition, in the present embodiment, even if not all synchronizing symbol is all known signal, as long as there is known signal according to certain intervals, also can utilize this known signal detected carrier frequency error.Can also use the different synchronizing symbol detected carrier frequency error of transmission means.
In the above-described embodiment, using synchronizing symbol corresponding to the subcarrier with every as processing object, but can also be using synchronizing symbol corresponding to the subcarrier with every M (M is more than 2 integer) as processing object.In this situation, can be that the 1st signal delay portion 46 and the 2nd signal delay portion 48 make inputted a signal delay M subcarrier.
Then, embodiments of the present invention 3 are described.Figure 11 is the functional block diagram of schematic configuration that the 1st 21B of frequency error detection portion of execution mode 3 is shown.As shown in figure 11, the 1st 21B of frequency error detection portion has synchronizing symbol extraction unit 31, the 1st complex operation portion 32, contrast signal supply unit 33B, correlation operation portion 36 and peak value test section 37.The structure of the receiving system of present embodiment is except the 1st 21B of frequency error detection portion, identical with the structure of the receiving system 1 of above-mentioned execution mode 1.
As shown in figure 11, contrast signal supply unit 33B comprise pre-stored have above-mentioned with reference to complex signal R(f
k) the 34B of signal storage portion.The 34B of this signal storage portion can be by the multiplying signal D(f with from 32 outputs of the 1st complex operation portion
k) corresponding to complex signal R(f
k) sequence offer correlation operation portion 36.
With reference to complex signal R(f
k) sequence to have be this character of fixed mode burst, therefore can be by with reference to complex signal R(f
k) pre-storedly in the 34B of signal storage portion, cut down operand.Now, the number of times of required complex multiplication is as follows in the present embodiment:
N×2。
Therefore for example, in the situation that being made as N=1024, D=200, operation times is 2048, compares with the operation times of the method for patent documentation 1, can access and be reduced to its effect of about 1/500.
Execution mode 4.
Then, embodiments of the present invention 4 are described.Figure 12 is the functional block diagram of schematic configuration that the 1st 21C of frequency error detection portion of execution mode 4 is shown.As shown in figure 12, the 1st 21C of frequency error detection portion has synchronizing symbol extraction unit 31, the 1st 32C of complex operation portion, contrast signal supply unit 33C, the 36C of correlation operation portion, peak value test section 37 and scope selection section 38.Contrast signal supply unit 33C comprises known signal generating unit 34 and the 2nd 35C of complex operation portion.
The structure of the receiving system of present embodiment is except the 1st 21C of frequency error detection portion, identical with the structure of the receiving system 1 of above-mentioned execution mode 1.In addition, the structure of the synchronizing symbol extraction unit 31 shown in Figure 12, known signal generating unit 34 and peak value test section 37 is identical with the structure of synchronizing symbol extraction unit 31, known signal generating unit 34 and the peak value test section 37 of above-mentioned execution mode 1 respectively.
The 1st 32C pair, the complex operation portion synchronizing symbol corresponding with subcarrier scope with the appointment of scope selected information carried out above-mentioned the 1st complex operation, and output is as the multiplying signal D(f of its operation result
k).The 2nd 35C of complex operation portion can be according to the output of scope selected information and multiplying signal D(f
k) corresponding to complex signal R(f
k).The 36C of correlation operation portion only carries out above-mentioned correlation operation for signal corresponding to the subcarrier scope with the appointment of scope selected information.
Thus, the 1st 21B of frequency error detection portion can only be used the impact due to multipath etc. to cause distortion is little and have a synchronizing symbol detected carrier frequency error of reliability.Figure 13 is the figure that summary illustrates the synchronizing symbol in synchronizing symbol in the scope that distortion is large and the little scope of distortion.In this case, by using the information of the synchronizing symbol of the subcarrier transmission in the scope that distortion is large regard the information that reliability is low as and get rid of outside operand, can only use the synchronizing symbol detected carrier frequency error in the little scope of distortion.Scope selection section 38 can be in the situation that more than being judged to be the subcarrier scope continued presence prescribed limit of signal quality good (distortion is little), export its scope selected information.
As described above, in the present embodiment, only use the synchronizing symbol detected carrier frequency error corresponding with the subcarrier scope with reliability, therefore, even in the situation that the distortion due to the impact of multipath etc. of the signal of synchronizing symbol, also can improve the accuracy of detection of carrier frequency error.
Then, embodiments of the present invention 5 are described.Figure 14 is the functional block diagram of schematic configuration that the 1st 21D of frequency error detection portion of execution mode 5 is shown.As shown in figure 14, the 1st 21D of frequency error detection portion has synchronizing symbol extraction unit 31, the 1st 32D of complex operation portion, contrast signal supply unit 33D, the 36D of correlation operation portion, peak value test section 37, scope selection section 38D, positional information storage part 39 and operand specifying part 40.Contrast signal supply unit 33D comprises known signal generating unit 34 and the 2nd 35D of complex operation portion.
The structure of the receiving system of present embodiment is except the 1st 21D of frequency error detection portion, identical with the structure of the receiving system 1 of above-mentioned execution mode 1.In addition, the structure of the synchronizing symbol extraction unit 31 shown in Figure 14, known signal generating unit 34 and peak value test section 37 is identical with the structure of synchronizing symbol extraction unit 31, known signal generating unit 34 and the peak value test section 37 of above-mentioned execution mode 1 respectively.
The positional information of the subcarrier that 39 storages of positional information storage part are selected in advance from an above-mentioned N subcarrier.Scope selection section 38D offers the 1st 32D of complex operation portion and the 2nd 35D of complex operation portion by the scope selected information of the subcarrier scope of the positional information appointment of selecting to be stored by positional information storage part 39.
The 1st 32D pair, the complex operation portion synchronizing symbol corresponding with subcarrier scope by the appointment of scope selected information carried out above-mentioned the 1st complex operation, and output is as the multiplying signal D(f of its operation result
k).The 2nd 35D of complex operation portion can be according to the output of scope selected information and multiplying signal D(f
k) corresponding to complex signal R(f
k).
On the other hand, 40 couples of 36D of correlation operation portion of operand specifying part specify the signal corresponding with the subcarrier scope of the positional information appointment of being stored by positional information storage part 39.Thus, the 36D of correlation operation portion only carries out above-mentioned correlation operation for the signal corresponding to subcarrier scope of the positional information appointment with being stored by positional information storage part 39.
Thus, by forming the 1st 21D of frequency error detection portion, even in the situation that the subcarrier of transmitting synchronous symbol has N, also only carry out complex operation and correlation operation for the K in this N subcarrier (K < N) subcarrier.Therefore, the operand of correlation operation can be reduced to K/N.
In addition, can substitute contrast signal supply unit 33D and use the 34B of signal storage portion of above-mentioned execution mode 2.Thus, can cut down operand.
Especially, positional information storage part 39 can be selected the positional information of subcarrier with the random interval of no regularity by storage, alleviate and receive signal to equate the impact of the multipath that subcarrier interval distortion is such.
Execution mode 6.
All or part of of the 1st frequency error detection portion 21 of above-mentioned execution mode 1～5, the function of 21B～21D can be realized by hardware resource, but also can realize by the cooperation of hardware resource and software.This function can be enough by comprising CPU(central processing unit: the computer program that microprocessor CPU) is carried out is realized.Active computer program realizes in the situation of a part of this function, and microprocessor can be by being written into this computer program and carrying out the part that realize this function the recording medium from embodied on computer readable.
This computer program can provide by being recorded in the recording medium of the embodied on computer readable such as CD, also can provide via communication lines such as the Internets.
Figure 15 illustrates with computer program to realize the 1st frequency error detection portion 21 of above-mentioned execution mode 1～5, the functional block diagram of the arithmetic unit 21E of the structure during function of 21B～21D.Random access memory) 52, nonvolatile memory 53, huge storage capacity recording medium 54, input/output interface 55 and bus 56 as shown in figure 15, this arithmetic unit 21E has processor 51, the RAM(Random Access Memory that comprises CPU:.As nonvolatile memory 53, for example, can use flash memory.In addition, as huge storage capacity recording medium 54, for example, can use hard disk (disk) or CD.Input/output interface 55 has the signal that the digital signal transmitting from DFT15 is sent to the function of processor 51 and will transmits from processor 51 and outputs to outside function.
Figure 16 is the flow chart of an example of the treatment step of the execution mode 6 when processor 51 being shown carrying out the computer program of function of the 1st frequency error detection portion 21 that realizes above-mentioned execution mode 1.
As shown in figure 16, processor 51 extracts synchronizing symbol (step S11) from the output of DFT15, and carries out above-mentioned the 1st complex operation (step S12).Figure 17 is the flow chart that summary illustrates the treatment step of the 1st complex operation.As shown in figure 17, processor 51 similarly makes synchronizing symbol postpone (step S21) with above-mentioned the 1st signal delay portion 46, and similarly carries out the complex multiplication (step S22) of the complex conjugate of Lag synchronization symbol and synchronizing symbol with the 1st complex multiplication portion 47.And, processor 51 similarly makes the multiplying signal obtaining in step S22 postpone (step S23) with above-mentioned the 2nd signal delay portion 48, and similarly carries out the complex multiplication (step S24) of the complex conjugate of this delay multiplying signal and multiplying signal with above-mentioned the 2nd complex multiplication portion 49.
Afterwards, as shown in figure 16, processor 51 is by generating known signal, carry out the function (step S13) of the contrast signal supply unit 33 in execution mode 1, for these known signals, carry out the 2nd complex operation (step S14), then with above-mentioned correlation operation portion 36 similarly when the relative position that makes subcarrier moves (step S17) calculate cross correlation value (step S15).Execution step S15 and S17 are until the signal within the scope of predetermined subcarrier is finished dealing with (step S16's is no).And, when the signal within the scope of predetermined subcarrier is finished dealing with (step S16 is), processor 51 is carried out the peak detection process (step S18) identical with above-mentioned peak value test section 37, and output represents the frequency error signal Ds1(step S19 of carrier frequency error).
Thus, present embodiment and above-mentioned execution mode 1 are same, detected carrier frequency error in the situation that not carrying out inverse fourier transform, so operand is less, and can cut down computing time and calculate required power consumption.
Execution mode 7.
Then, embodiments of the present invention 7 are described.The flow chart of one example of the treatment step of the execution mode 7 when Figure 18 is the computer program of processor 51 that Figure 15 the is shown function of carrying out the 1st 21B of frequency error detection portion that realizes above-mentioned execution mode 3.
The flow chart of Figure 18 has except substituting step S13, the S14 of Figure 16 the aspect of step S13B, identical with the flow chart of Figure 16.In step S13B, processor 51 is same with the above-mentioned signal storage 34B of portion, from nonvolatile memory 53, reads with reference to complex signal R(f
k) sequence and supply with.Therefore, can similarly cut down operand with execution mode 3.
Above, with reference to accompanying drawing, narrated various execution mode of the present invention, but they are only all illustrations of the present invention, can also adopt above-mentioned variety of way in addition.For example, in above-mentioned execution mode 1～5, the 1st complex multiplication portion 47 is by the complex conjugate complex multiplication of Lag synchronization symbol and input synchronizing symbol, the 2nd complex multiplication portion 49, by the complex conjugate complex multiplication of the multiplying signal that postpones multiplying signal and input from the 1st complex multiplication portion 47, is still not limited to this.For example, also have following mode: the 1st complex multiplication portion 47 carries out complex multiplication by the complex conjugate of input synchronizing symbol and Lag synchronization symbol, the 2nd complex multiplication portion 49 carries out complex multiplication by the complex conjugate of the multiplying signal from 47 inputs of the 1st complex multiplication portion and delay multiplying signal.In this situation, the 2nd complex multiplication portion 49 also can export the multiplying signal of eliminating after phase rotating component.
Claims (10)
1. a frequency error detection device, it is detected carrier frequency error in receiving system, described receiving system has: acceptance division, it receives and uses a plurality of subcarriers with the subcarrier frequency differing from one another to carry out the transmitted signal frequency division multiplexing, the reception signal of outgoing carrier frequency band from transmitter; Quadrature demodulation portion, it carries out quadrature demodulation and generates complex baseband signal described reception signal; And orthogonal transform portion, it implements orthogonal transform to described complex baseband signal, generates the complex symbol signal of frequency domain, and described frequency error detection device is characterised in that to have:
Known signal extraction unit, it extracts and receives known signal from described complex symbol signal;
Complex operation portion, its sequence to described reception known signal is carried out the 1st complex operation, eliminates thus the phase rotating component of giving described reception known signal when described orthogonal transform;
Contrast signal supply unit, it provides with reference to complex signal sequence, and this is by the identical known signal sequence of the known signal sequence to using in described transmitter, to carry out 2nd complex operation identical with described the 1st complex operation to generate with reference to complex signal sequence;
Correlation operation portion, it calculates from sequence and described a plurality of distributions with reference to the cross correlation value between complex signal sequence of the complex signal of described complex operation portion output; And
Peak value test section, it detects the distribution with peak-peak from described a plurality of distributions,
Described a plurality of distribution is calculated with respect to the described relative position with reference to complex signal sequence on frequency axis by the described correlation operation portion repeatedly sequence of mobile described complex signal,
Described peak value test section, according to the departure of the described relative position corresponding with the distribution with described peak-peak, detects described carrier frequency error.
2. frequency error detection device according to claim 1, is characterized in that,
Described complex operation portion comprises:
The 1st signal delay portion, it postpones and output delay known signal described reception known signal;
The 1st complex multiplication portion, it is multiplied by the opposing party's complex conjugate to the side in described reception known signal and described delay known signal, the sequence of output the 1st multiplying signal;
The 2nd signal delay portion, it postpones and the sequence of output delay multiplying signal described the 1st multiplying signal; And
The 2nd complex multiplication portion, it is multiplied by the opposing party's complex conjugate to the side in described the 1st multiplying signal and described delay multiplying signal, the sequence of output the 2nd multiplying signal.
3. frequency error detection device according to claim 1 and 2, is characterized in that,
Described frequency error detection device also has scope selection section, and described scope selection section is judged the signal quality of described reception known signal, and according to its result of determination is selected should be as the scope of the signal of the object of described the 1st complex operation,
Described complex operation portion in the sequence of described reception known signal, by the reception known signal in the selected scope of described scope selection section, carry out described the 1st complex operation.
4. frequency error detection device according to claim 1 and 2, is characterized in that,
Described frequency error detection device also has the positional information storage part of the positional information that stores the subcarrier of selecting in advance from described a plurality of subcarriers,
Described complex operation portion in the sequence of described reception known signal, the reception known signal corresponding with subcarrier by described positional information appointment carry out described the 1st complex operation,
Described correlation operation portion calculates described with reference to corresponding a plurality of with reference to complex signal with from a plurality of distributions of the cross correlation value between the sequence of the complex signal of described complex operation portion output of the subcarrier with by described positional information appointment in the sequence of complex signal.
5. a receiving system, is characterized in that, described receiving system has:
Acceptance division, its transmitted signal from transmitter receives the frequency division multiplexing that has used a plurality of subcarriers with the subcarrier frequency differing from one another, the reception signal of outgoing carrier frequency band;
Local oscillator, its generation has the oscillator signal of local oscillation frequency;
Quadrature demodulation portion, it uses described oscillator signal to carry out quadrature demodulation and generate complex baseband signal described reception signal;
Orthogonal transform portion, it implements orthogonal transform to described complex baseband signal, generates the complex symbol signal of frequency domain;
Known signal extraction unit, it extracts and receives known signal from described complex symbol signal;
Complex operation portion, its sequence to described reception known signal is carried out the 1st complex operation, eliminates thus the phase rotating component of giving described reception known signal when described orthogonal transform;
Contrast signal supply unit, it provides with reference to complex signal sequence, and this is by the identical known signal sequence of the known signal sequence to using in described transmitter, to carry out 2nd complex operation identical with described the 1st complex operation to generate with reference to complex signal sequence;
Correlation operation portion, it calculates from sequence and described a plurality of distributions with reference to the cross correlation value between complex signal sequence of the complex signal of described complex operation portion output; And
Peak value test section, it detects the distribution with peak-peak from described a plurality of distributions,
Described a plurality of distribution is calculated with respect to the described relative position with reference to complex signal sequence on frequency axis by the described correlation operation portion repeatedly sequence of mobile described complex signal,
Described peak value test section detects described carrier frequency error according to the departure of the described relative position corresponding with the distribution with described peak-peak,
Described local oscillator is so that the mode that described carrier frequency error reduces is controlled described local oscillation frequency.
6. receiving system according to claim 5, is characterized in that,
Described receiving system also has scope selection section, and described scope selection section is judged the signal quality of described reception known signal, and according to its result of determination is selected should be as the scope of the signal of the object of described the 1st complex operation,
Described complex operation portion in the sequence of described reception known signal, by the reception known signal in the selected scope of described scope selection section, carry out described the 1st complex operation.
7. receiving system according to claim 5, is characterized in that,
Described receiving system also has positional information storage part, and this positional information storage portion stores has the positional information of the subcarrier of selecting in advance from described a plurality of subcarriers,
Described complex operation portion in the sequence of described reception known signal, the reception known signal corresponding with subcarrier by described positional information appointment carry out described the 1st complex operation,
Described correlation operation portion calculates described with reference to corresponding a plurality of with reference to complex signal with from a plurality of distributions of the cross correlation value between the sequence of the complex signal of described complex operation portion output of the subcarrier with by described positional information appointment in complex signal sequence.
8. a frequency error detecting method, it is the frequency error detecting method of detected carrier frequency error in receiving system, the transmitted signal of described receiving system from transmitter receives the frequency division multiplexing used a plurality of subcarriers with the subcarrier frequency differing from one another the reception signal of outgoing carrier frequency band, described reception signal is carried out quadrature demodulation and generates complex baseband signal, described frequency error detecting method is characterised in that to have following steps:
From the complex symbol signal by described complex baseband signal enforcement orthogonal transform is generated, extract and receive known signal;
The sequence of described reception known signal is carried out to the 1st complex operation, eliminate thus the phase rotating component of giving described reception known signal when described orthogonal transform;
Provide with reference to complex signal sequence, this is by the identical known signal sequence of the known signal sequence to using in described transmitter, to carry out 2nd complex operation identical with described the 1st complex operation to generate with reference to complex signal sequence;
Repeatedly mobile described with reference to complex signal sequence with respect to the complex signal sequence of the execution result as described the 1st complex operation the relative position on frequency axis, calculate described complex signal sequence and described a plurality of distributions with reference to the cross correlation value between complex signal sequence;
From described a plurality of distributions, detect peak-peak; And
Departure according to the described relative position corresponding with described peak-peak, detects described carrier frequency error.
9. frequency error detecting method according to claim 8, is characterized in that,
Described frequency error detecting method also has following steps: judge the signal quality of described reception known signal, and according to its result of determination is selected should be as the scope of the signal of the object of described the 1st complex operation,
Reception known signal in scope in the sequence of described reception known signal, that this is selected is carried out to described the 1st complex operation.
10. frequency error detecting method according to claim 8, is characterized in that,
Described frequency error detecting method also has the step of reference position information storage part, and described positional information storage portion stores has the positional information of the subcarrier of selecting in advance from described a plurality of subcarriers,
To in the sequence of described reception known signal, the reception known signal corresponding with subcarrier by described positional information appointment carry out described the 1st complex operation,
The distribution of described cross correlation value is described with reference to a plurality of distributions with reference to the cross correlation value between complex signal and the sequence of described complex signal corresponding to the subcarrier with by described positional information appointment in complex signal sequence.
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| JP2012187725A JP5984583B2 (en) | 2012-08-28 | 2012-08-28 | Frequency error detection apparatus, frequency error detection method, and reception apparatus |
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| JP2021114677A (en) * | 2020-01-17 | 2021-08-05 | 株式会社東芝 | Communication relay device, control method, and program |
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| US20100226467A1 (en) * | 2009-03-03 | 2010-09-09 | Kabushiki Kaisha Toshiba | Frame number detecting device |
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| CN109964426B (en) * | 2016-10-31 | 2022-02-18 | 杜塞尔多夫华为技术有限公司 | Signal receiver and method for analyzing received signal, communication system |
Also Published As
| Publication number | Publication date |
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| CN103685122B (en) | 2016-12-28 |
| DE102013217141A1 (en) | 2014-03-06 |
| JP5984583B2 (en) | 2016-09-06 |
| JP2014045433A (en) | 2014-03-13 |
| DE102013217141B4 (en) | 2021-10-28 |
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